Illinois
Mazon Creek (Pit 11 / Braidwood spoil piles)
Fossil site Documented siteGray area
What you could find
Reported finds from this ground.
Crystals and mineralsAlso reported: Siderite concretions with Tullimonstrum, ferns, shrimp, jellyfish (Essex/Braidwood biota).
Photos via Wikimedia Commons: Stephanie Clifford from Arlington, VA, USA (CC BY 2.0).
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Why this spot
Pennsylvanian
World-famous soft-body concretions. Access has tightened; check current SFWA/landowner rules.
Keep exploring nearby
More spots in this area.